1. Field of the Invention
This invention relates to tapes and is concerned with tapes suitable for use as teartapes.
2. Description of the Prior Art
Teartapes are known to provide a means of facilitating the opening of packages such as packs of cigarettes, confectionery and like including overwrapping formed from filmic packaging materials. They are adhered to the surface of the packaging material in a manner such that, in use, an end of the teartape can be pulled so as to tear the packaging material underlying the teartape to allow access to the contents.
Traditionally such teartapes have been made from cellulose film or derivatives of cellulose which are coated with barrier resistant and/or heat seal coatings. Such tapes can be readily applied to packaging material formed from films of a similar material by moistening the coating with a solvent, to soften the coating, and applying heat and pressure to give firm adhesion. The replacement of cellulose-based packaging material by stronger and more cost effective polyolefin film packaging materials, and especially by biaxially oriented polypropylene films, has similarly led to the substitution of polypropylene for cellulose in teartape manufacture.
Polypropylene teartapes often comprise two-ply laminates of similar polypropylene film to provide increased tear strength and, also, to protect any print applied to the surface of the lower layer. Two methods have been employed to apply these polypropylene tapes to polyolefin film packaging materials. In the case where the polyolefin packaging material is a lacquer coated film, a solvent is used to activate the coating and ensure adhesion of the tear tape. Alternatively, if the polyolefin packaging material is uncoated, the teartape is caused to adhere by applying a hot melt wax composition. A lacquer coating is not usually, a packaging requirement, when using polyolefin packaging film, since these have superior barrier properties to cellulose films. Also, in the case of polyolefins there is the opportunity to co-extrude films in order to provide for any specially demanding barrier properties. Hence, the use of lacquer coated polyolefin packaging film simply to promote the adhesion of a teartape involves an unacceptable cost penalty. The use of hot melt wax compositions is, also, undesirable since this gives rise to:
1. the need for cleaning, PA1 2. the need for close attention by the operator to recharge the baths with adhesive wax and to ensure temperatures are correct in order to promote satisfactory adhesion, PA1 3. a safety hazard with high temperature wax baths, PA1 4. distortion of the packaging film and/or tape as a consequence of the heat of application or stress on cooling which can cause an unsightly "cockling" effect, and PA1 5. poor and inconsistent adhesion to film, especially, on starting and restarting the lamination process. PA1 (a) a support means for receiving a reel of tape, the reel rotating as tape is drawn from the reel by said moving surface, PA1 (b) a guide means defining a tape path from the reel to said location, PA1 (c) a brake means for reducing the speed of rotation of the reel in dependence on a reduction in tension of the tape passing along said tape path, and PA1 (d) a drive means for increasing the speed of rotation of the reel in dependence on an increase in tension of the tape passing along said tape path.
These disadvantages are particularly troublesome when stopping and starting the application of the teartapes to the packaging film and the nature of the teartapes and their means of application are such that relatively small spools of tape containing no more than 2500-5000 meters have had to be used, thus, causing frequent stoppages on fast operating packaging lines. The present invention provides a teartape suitable for applying to polyolefin film packaging materials without the foregoing disadvantages.